The entire disclosure of Japanese Patent Application No. Hei 10-123193 filed on May 6, 1998, another Japanese Patent Application No. Hei 10-370637 filed on Dec. 25, 1998, and another Japanese Patent Application No. Hei 11-107209 filed on Apr. 14, 1999, including specification, claims, drawings and abstract is incorporated herein by reference in its entirety.
1. Field of the Invention
This invention relates to digital data communication systems, more specifically to communications of self-descriptive data.
2. Description of the Related Art
Nowadays, a communication method using the internet is known as two-way data communications among computers. The principle of the method will be briefly described hereunder. A plurality of hyper text markup language (hereinafter referred to as HTML) files linked with one another are stored into a world wide web (hereinafter referred to as WWW) server which is connected to the internet. A demand for transmitting the HTML files stored in the WWW server is sent thereto from a gathering information computer which is connected to the internet. The WWW server transmits whole or a part of the HTML files to the gathering computer in response to the demand. As a result, data linked with one another and stored in the WWW server can be transferred.
Data communication services using satellite broadcasting, on the other hand, are known as one-way data communications. In satellite broadcasting, data are transmitted through a moving picture experts group 2 (hereinafter referred to as MPEG 2) system standard used for data transmission which has a relatively higher flexibility than the other two standards in the MPEG 2, such as MPEG 2 video standard used for video data and MPEG 2 audio standard used for audio data, out of these three MPEG 2 standards.
In order to transmit HTML files to the receivers by using satellite broadcasting, a demand for transmitting desired HTML file(s) need to be sent to the transmitter.
To avoid sending the demand, methods described hereunder are employed in actual data communications protocols such as BITCAST and ADAMS (TV-Asahi data and multimedia service). A plurality of files linked with one another are transmitted as one unitized file by the transmitter. In the receiver, all the files are stored in a storage device like a hard disk by sequentially storing each of the files therein. Further, the specified file(s) is displayed in response to operation of the user by browser software installed in the receiver. The browser software performs reference operations by specifying the name of a file(s) stored in a hard disk when there is HTML tag(s) requiring reference of other file(s) in the specified file(s) (details of the technology is disclosed in an article entitled xe2x80x9cSpecial Report from state-of-the-art technology; The Whole Aspect of the Next Generation Digital Televisionxe2x80x9d, published by Nikkei Business Publications, Inc.)
In this method, however, all the files must be stored in the hard disk as well as storing information needed to manage the directory. In this way, a certain capability for storing this information is required in the receiver, and the receiver can not display a desired file(s) until its retrieval is completed. Further, a number of processing steps need to be performed by the receiving computer""s central processing unit (CPU) for retrieving the desired file(s) from the stored files.
It is an object of the present invention to overcome the above mentioned drawbacks on the data communication method, and to provide a data communication system and a method thereof capable of selectively receiving selected data out of data consisting of a plurality of files related one another at a high speed with less data storing capacities.
It is another object of the present invention to provide a data communication system and a method thereof capable of selectively extracting desired data out of data related with one another even when the receiver has a small data storing capability.
In accordance with characteristics of the present invention, there is provided a digital data communication system comprising a transmitter and a receiver,
A) the transmitter including:
a1) file storing means for storing a plurality of files, and
a2) transmission means for repeatedly transmitting the files packetized thereby in accordance with a transmission protocol, the packetized files uniquely assigned identifiers;
B) the receiver including:
b1) selective receiving means for selectively receiving the packetized files having predetermined identifiers in accordance with a selecting condition set therein and outputting data contained in the packetized files,
b2) display data generating means for generating display data according to the outputted data, and
b3) selecting condition varying means for varying the selecting condition; and
C) wherein c1) the file storing means stores files formed of self-descriptive data which includes a reference command for referring another file, and wherein the identifier of each file includes characters directly selected by the selecting condition varying means,
c2) the display data generating means generates display data according to the self-descriptive data outputted by the selective receiving means, and
c3) the selecting condition varying means provides an identifier assigned to a file so as to obtain the file specified by the reference command in the self-descriptive data to the selective receiving means.
Also, in accordance with characteristics of the present invention, there is provided a method of communicating digital data, comprising the steps of:
repeatedly transmitting a plurality of files after packetizing the files according to a transmission protocol with identifiers uniquely assigned thereto in a transmitting station, each of the files comprising self-descriptive data which include a reference command for referring another file, the identifier of the each file consisting of characters directly selected by a receiving station, and
performing the following steps in a receiving station, selectively receiving the packetized files having predetermined identifiers in accordance with a selecting condition set therein, generating display data in accordance with the self-descriptive data contained in the packetized files, outputting the generated data, and varying an identifier of a file as the selecting condition so as to obtain the file specified by the reference command in the self-descriptive data.
Further, in accordance with characteristics of the present invention, there is provided a digital data communication system comprising a transmitter and a receiver,
A) the transmitter including:
a1) file storing means for storing a plurality of files, and
a2) transmission means for repeatedly transmitting the files packetized thereby in accordance with a transmission protocol, the packetized files uniquely assigned identifiers;
B) the receiver including:
b1) selective receiving means for selectively receiving the packetized files having predetermined identifiers in accordance with a selecting condition set therein and outputting data contained in the packetized files,
b2) received data storing means for storing data contained in the packetized files each having same identifier in one independent file basis,
b3) display data generating means for generating display data according to the outputted data, and
b4) selecting condition varying means for varying the selecting condition; and
C) wherein: c1) the file storing means stores files formed of self-descriptive data which includes a reference command for referring another file,
c2) the transmission means assigns one module identifier including characters capable of being read directly with the selective receiving means to both a reference file which refers other files and a referred file which is referred by the reference file, and transmits the reference file and the referred file, and
c3) the display data generating means generates display data according to the self-descriptive data contained in the reference file, and generates another display data according to a desired referred file which is read out thereby from the received data storing means.
In accordance with characteristics of the present invention, there is provided a method of communicating digital data, comprising the steps of:
repeatedly transmitting a plurality of files stored in a transmitting station after packetizing the files according to a transmission protocol with identifiers uniquely assigned thereto in the transmitting station, and
performing the following steps in a receiving station, selectively receiving the packetized files having predetermined module identifiers in accordance with a selecting condition set therein, storing data contained in the packetized files each having same identifier in one independent file basis, and generating display data according to the outputted data,
wherein one module identifier including characters capable of being read directly with the receiving station is assigned to both a reference file which refers other files and a referred file which is referred by the reference file in the transmitting station,
wherein the following steps are performed by the receiving station, the selecting condition is varied so as to selectively receive packetized files each assigned same identifier with that of a specific reference file in order to selectively receive the specific reference file, display data is generated according to self-descriptive data contained in the reference file, and generating another display data according to a desired referred file which is read out thereby.
Also, in accordance with characteristics of the present invention, there is provided a digital data communication system comprising a transmitter and a receiver,
A) the transmitter including:
a1) file storing means for storing a plurality of files, and
a2) transmission means for repeatedly transmitting the files packetized thereby in accordance with a transmission protocol, the packetized files uniquely assigned identifiers;
B) the receiver including:
b1) selective receiving means for selectively receiving the packetized files having predetermined identifiers in accordance with a selecting condition set therein and outputting data contained in the packetized files,
b2) received data storing means for storing data contained in the packetized files each having same identifier in one independent file basis,
b3) display data generating means for generating display data according to the outputted data, and
b4) selecting condition varying means for varying the selecting condition; and
C) wherein c1) the file storing means stores a plurality of reference files formed of self-descriptive data which includes a reference command for referring a plurality of other files,
c2) the transmission means assigns one module identifier including characters capable of being read directly with the selective receiving means to the reference files and transmits the reference files,
c3) the display data generating means generates display data according to self-descriptive data contained in the reference files, and generates another display data according to desired referred files which are read out thereby from the received data storing means, and
c4) the selecting condition varying means uses the module identifier as the selecting condition.
Further, in accordance with characteristics of the present invention, there is provided a digital data receiver comprising:
selective receiving means for selectively receiving packetized files having predetermined identifiers in accordance with a selecting condition set therein and outputting data contained in the packetized files,
received data storing means for storing data contained in the packetized files each having same identifier in one independent file basis;
display data generating means for generating display data according to the outputted data; and
selecting condition varying means for varying the selecting condition;
wherein the packetized files thus received are one of a reference file formed of self-descriptive data which includes a reference command for referring another file and a referred file by the reference file, and one identifier including characters capable of being read directly with the selective receiving means is assigned to these files,
and wherein the display data generating means generates display data according to self-descriptive data contained in the reference file, and generates another display data according to a desired referred file which is read out thereby from the received data storing means,
and wherein the selecting condition varying means extracts characters directly be selected by the selective receiving means out of absolute path assigned to the referred files and provides the characters to the selective receiving means as the selecting condition so as to selectively receive packetized files each assigned same identifier with that of the reference file in order to selectively receive the reference file. While the novel features of the invention are set forth in a general fashion, both as to organization and content, the invention will be better understood and appreciated, along with other objects and features thereof from the following detailed description taken in conjunction with the drawings.